The tracefnt package provides for tracing the actions concerned with
loading, substituting and using fonts.
The package accepts the following options:

errorshow

Write all information about font changes, etc. but
only to the transcript file unless an error occurs. This means that
information about font substitution will not be shown on the
terminal.

warningshow

Show all font warnings on the terminal. This
setting corresponds to the default behaviour when this
tracefnt package is not used!

infoshow

Show all font warnings and all font info messages
(that are normally only written to the transcript file) also on the
terminal. This is the default when this tracefnt package is
loaded.

debugshow

In addition to what is shown by infoshow,
show also changes of math fonts (as far as possible): beware, this
option can produce a large amount of output.

loading

Show the names of external font files when they are
loaded. This option shows only `newly loaded' fonts, not those
already preloaded in the format or the class file before this
tracefnt package becomes active.

pausing

Turn all font warnings into errors so that LaTeX will stop.

Warning: The actions of this package can change the layout of a
document and even, in rare cases, produce clearly wrong output, so
it should not be used in the final formatting of `real documents'.